Core D. Biostatistics and Data Management Core The Biostatistics and Data Management Core (BDM) will provide data and statistical support services for all phases of the individual projects, as needed. This includes developing analysis plans and designing data collection forms and protocols in consultation with the individual Project Leaders. The BDM Core will coordinate data entry and quality control procedures. The Core will be responsible for data management and consolidation of different datasets for analysis. Following the analysis plans, staff from the BDM core will perform interim and final data analyses under the supervision of the Core Leader, Dr. Leann Myers. Staff will provide written and graphical/tabular summaries of the analysis as well as journal-appropriate Statistical Methods and Results sections for publication and presentation. Staff from the BDM core will help design future studies, including sample size and power estimates and analysis plans. The Biostatistics and Data Management Core will be responsible for backing-up and storing working and final datasets, following a backup schedule determined in consultation with the Project Leaders. An additional responsibility will be to provide access to finalized data sets to other researchers in accordance with NIH data sharing provisions. The use of a centralized core for statistical support relieves the individual researcher of the responsibility for these functions, and insures consistent and efficient data handling. Use of a common core also allows for easier connections across projects and the development of statistical methods appropriate to STI data